Beyond the firm contract, Virgin Galactic has placed an additional agreement to provide OneWeb with options for up to 100 additional launches.
The announcement coincides with an announcement by OneWeb regarding $500m of new investment. The project is backed by world-class equity partners including Airbus Group, Intelsat, Qualcomm, The Coca-Cola Company and the Virgin Group.
OneWeb wants to develop a global wireless communications and data system that will enable affordable broadband access anywhere in the world, including in areas currently not served by terrestrial providers.
Virgin Galactic CEO George Whitesides said: "The scale of this order will drive our manufacturing rates to achieve unprecedented cost reductions for small satellite launch. We are excited to support OneWeb and its partners as they harness the potential of small satellites to create new opportunities for all."